Very unlikely that the wires have anything to do with filtering, probably a last minute fix of PCB layout errors.
The Aztech has absolutely no documentation that I could find about their chips.

There is a datasheet on the Analog Devices codec chip, but my knowledge of these is practically zero.
So, even if I could see where the wires were connected to on the codec chip, I wouldn't understand what its purpose is 🤣.

Alternatively, someone with the same model could test the sound output and let me know whether they experience the same "filtered" sound playback.
Not that it's a big problem. I'm just intrigued by this.

Nothing regarding filtering. It looks like those are read strobe (RDn) and chip select (CSn) pins, but frankly the picture is not so good as it looks like the other green wire is not directly connected to AD chip.

So perhaps they had CS and RD accidentally swapped so they had to mod it, and either next versions had fixed PCB layout to connect them right or then they fixed the Aztech custom ASIC pins to connect them right.

Jepael wrote:

Nothing regarding filtering. It looks like those are read strobe (RDn) and chip select (CSn) pins, but frankly the picture is not so good as it looks like the other green wire is not directly connected to AD chip.

So perhaps they had CS and RD accidentally swapped so they had to mod it, and either next versions had fixed PCB layout to connect them right or then they fixed the Aztech custom ASIC pins to connect them right.

That makes sense.
Could a bad capacitor lead to "filtered" output?
If so, which one(s) could most likely be the culprits?

jesolo wrote:

Could a bad capacitor lead to "filtered" output?
If so, which one(s) could most likely be the culprits?

It could, but it's just more likely it just has less treble by design, because of the mixer chip settings or component values in the audio paths. If there's no data on the mixer chip, we can't really tell.

Does WSS audio (from the AD1848) also sound muffled?

Jepael wrote:

Does WSS audio (from the AD1848) also sound muffled?

No, it's only the Sound Blaster (8-bit) part that sounds "muffled".
It's not that bad, but after reading James-F's other thread around the output filters on the Sound Blaster Pro, I decided to test out my older cards.

I also have an NXPro, which only has 8-bit output. When I enable that card's output filter, it sounds very much the same as this card's output (despite not having an output filter).

It's possible, as you've stated, that this is by design.

I vaguely recall back in the day of this card's output not always being that clear, but its been a while since I've used it.
It has always been stored in its anti static bag under fairly moderate temperatures.

Although, technically, that is how it is supposed to sound, one is used to hearing cleared (unfiltered) sound output on these older cards.

I guess the only way to confirm this is for someone else, with a similar model, to confirm this. I think the NXPro 16 also had the same components.

The couple of Aztech based cards I've tried have sounded very muffled - both the SB 2.0 and SB Pro Aztech. I think I described it at the time as it being like my speakers were immersed in water.